Toward Quantum Computing with Molecular Magnets: Studies of Spin Dynamics in a Radiation Field

乔纳森·R·弗里德曼·阿默斯特学院使用分子磁铁进行量子计算的进展；自旋动力学研究将分子磁铁用作量子比特的可行性正在研究中，量子计算机的处理元件通过使用脉冲微波和毫米波辐射对这些系统的自旋态进行量子操作。在此过程中，还研究了这些体系的磁矩在低于几开尔文的温度下反向隧穿机制的一些重要问题。我们正在进行一系列实验，以测量外加辐射对分子磁体磁弛豫的影响。这些实验包括光子辅助弛豫，当辐射帮助分子的自旋方向相反时发生，反转几率随辐射脉冲持续时间的拉比振荡，以及由一系列辐射脉冲产生的自旋态的量子叠加的自由进动。这些实验的目的是提供激发自旋态的退相干时间的测量，这是确定分子磁体是否可以用作量子比特的关键参数。该项目还在研究缓解由于与邻近分子的偶极相互作用、核自旋和缺陷而产生的非均匀展宽效应的方法。该项目对量子计算和信息存储领域具有潜在的影响。它还促进了本科生的教育，特别是像女性和少数民族这样代表不足的群体。

EIA-0218469Jonathan R. FriedmanAmherst CollegeToward Quantum Computing with Molecular Magnets; Studies of Spin DynamicsThe viability for using molecular magnets as qubits, the processing elements of quantum computers by using pulsed microwave and millimeter-wave radiation to perform quantum operations on the spin states of these systems are being investigated. In the process, some important issues regarding the tunneling mechanism by which the magnetic moments of these systems reverse direction at temperatures below a few Kelvin are also investigated.A series of experiments are being performed to measure the effect of the applied radiation on the magnetic relaxation of the molecular magnets. These experiments include photon-assisted relaxation, which occurs when the radiation helps the molecule's spin reverse direction, Rabi oscillations of the probability of reversal with radiation-pulse duration, and free-precession of a quantum superposition of spin states produced by a series of radiation pulses. These experiments are aimed at providing a measure of the decoherence time of the excited spin state, a crucial parameter for determining whether the molecular magnets can be used as qubits. The project is also investigating methods of mitigating inhomogeneous broadening effects due to dipole interactions with neighboring molecules, nuclear spins and defects.The project has potential impacts for the fields of quantum computation and information storage. It is also promoting the education of undergraduate students, especially underrepresented groups like women and minorities.